Invoice Due Date Calculator Formula

Understand the math behind the invoice due date calculator. Each variable explained with a worked example.

Use the Invoice Due Date Calculator

Formulas Used

Days Until Payment Due

days_until_due = invoice_days

Weeks Until Due

weeks_until_due = invoice_days / 7

Amount Due

invoice_total = invoice_amount

Variables

VariableDescriptionDefault
invoice_daysPayment Terms30
invoice_amountInvoice Amount(USD)5000

How It Works

Understanding Invoice Payment Terms

Common Terms

  • Net 30 -- Payment due within 30 days of the invoice date
  • Net 60 -- Payment due within 60 days
  • Net 90 -- Payment due within 90 days
  • Net 10 -- Payment due within 10 days (often used with early payment discounts)

    • The "net" refers to the total amount due. Payment terms are counted from the invoice date, not the date of service.

    Worked Example

    An invoice for $5,000 with Net 30 terms.

    invoice_days = 30invoice_amount = 5000
    1. 01Payment terms: Net 30
    2. 02Days until payment is due: 30 days
    3. 03Weeks until due: 30 / 7 = 4.3 weeks
    4. 04Amount due: $5,000

    Ready to run the numbers?

    Open Invoice Due Date Calculator